This invention relates generally to techniques of exposing an eye to electromagnetic radiation for the purpose of treatment, and, more specifically, to an improved apparatus that controllably directs a defined pattern of electromagnetic radiation to a cornea for the purpose of reshaping the cornea.
Although there are many specific treatment procedures involving the necessity for directing a highly controlled beam of electromagnetic radiation to an eye, keratoplasty procedures are currently receiving a great deal of attention because of their ability to correct an eye for nearsightedness, farsightedness and/or astigmatism. In one surgical procedure, a radiation beam is used to cut controlled portions of the cornea by ablation of tissue in its path. One specific application of this procedure is in the performance of a radial keratotomy procedure without the necessity of using a knife to make radial cuts in the cornea. In another specific application, an outside surface of the cornea removed by an eximer laser in order to reshape it.
An alternative procedure, which avoids cutting the cornea, directs one or more focused beams of electromagnetic radiation within the infrared portion of the spectrum into the eye to thermally shrink collagen tissue within the cornea in order to cause corrective changes in the cornea curvature. This later technique, often termed photothermal keratoplasty (PTK), is the subject of U.S. Pat. Nos. 4,976,709 and 5,618,284 to Dr. Bruce J. Sand, which patents are expressly incorporated herein in their entirety by this reference. The collagen shrinkage technique promises to provide permanent changes to the optical characteristics of the human cornea with a higher degree of safety and patient comfort than is the case with techniques that involve physically cutting and removing portions of the cornea.
One way to deliver a desired electromagnetic radiation pattern to the cornea is by projection from a short distance removed from the cornea. One instrument for doing so is described in international PCT application publication no. WO 94/03134 (hereinafter "PCT Publication"), which publication is hereby incorporated herein in its entirety by this reference. That described instrument allows an ophthalmologist, or other attending physician or practitioner, to select and deliver a specific pattern and amount of electromagnetic radiation to each patient in accordance with the condition to be corrected. It is desirable for such an instrument to efficiently perform corrective photothermal keratoplasty procedures on a large number of patients with a high degree of accuracy, effectiveness, safety and convenience.
Therefore, it is also an object of at least one aspect of the present invention to provide an instrument, including but not limited to the type of the PCT Publication, that operates with a high degree of accuracy, effectiveness, safety and convenience to project controlled patterns of treatment radiation onto a cornea being treated.
It is another object of at least one aspect of the present invention to provide a system, including but not limited to the type of the PCT Publication, for remotely linking a number of geographically dispersed medical treatment instruments with a central computer database for useful purposes.
It is a further object of at least one aspect of the present invention to provide an improved method and system, including but not limited to the type of the PCT Publication, for projecting a controlled pattern of infrared radiation against the cornea of the eye in performance of photothermal keratoplasty procedures.